This project has several components related to different biomedical instrumentation modalities. One type of study is to find optimal designs for measuring in vivo first-order rate constants by means of NMR magnetization transfer experiments. It is important to make these measurements as quickly as possible to minimize artifacts due to physiological changes that might occur during the course of the experiment. In the course of a project currently being completed, an easily-implemented optimal experiment was designed, using the assumption that the experimenter knows an a priori range for the rate constant, but also that the associated spin-lattice relaxation time (T1) is known. This somewhat artificial assumption is dropped in the current approach to this problem. A project related to many aspects of medical imaging has required the development of a simulation package to examine problems raised by positron-emission tomography (PET) and single-photon emission tomography (SPECT). For this purpose, a currently available program (SIMSET, developed at the University of Washington) has been modified to more accurately model the design of equipment in general hospital use. Several projects using this program will be undertaken in the coming year.